Shoe stiffener and method of making it



Patented NOV. 3, 1925.

Unirse stares 'Perrammen(j ERED RICKs,Y or LEICESTER, ENGLANn, AssIeNoR To UNITED sIIoE MACHINERYA CORPORATION, OE PATEnsON, NEW JERSEY, A CORPORATION OE NEWJERSEY.

SHOE STIEEENER AND METHOD OE iyIAKINerI'i.`

Application mea october 18, l1923. seriai rseegiaiaf(Y To all whom it may cof/wem.'

Be it known that l, FRED'RICKS, a sube` on the drawings indicating like parts in the Y several figures.

This invention relates to thermoplastic stiffeners for parts of boots and shoesl and to a method of making them, and is herein set forth in connection with a toe stiffener. The term thermoplastic denotes that quality of a. substance whereby it is .hard and somewhat resilient` at ordinary temperatures but may be rendered plastic enough by heat to be molded. A toe lstiffener of the thermoplastic type and the method of using it is disclosed, for example, in Patent No. 1,12%,835-f y Tliermoplastic toe stitleners, as heretofore used, have commonly consisted ot a blank ofY felt impregnated with a thermoplastic agent such, for example, as a mixture of 75% of colophony and 25% vof blown asphalt, Such stitfeners are incorporated in boots and shoes by inserting them in place'V in the boot or shoe, heating them to render them limp and plastic, and then molding 1 'them to the desired shape during'the'lastfined ridge shall shoe or become evident after the shoe has ing operation.

In the manufacture of sO-called softtoed shoes or plain vamp shoesl7 which have iio'toe cap or tip, it is particularly desirable to' secure a gradual blending, in point of vresilience or pliability, between the stitened toe portion and the upper adjacent to the toe portion so `that no sharply debe visible inthe finished been worn. l y y The present'invention has particularly for its object to provide stiifeners of the said type which shall be well adapted for use in plain vamp shoes to stiften the toe portions tliereof without showing through the upper leather an imprint or the stiflener along the rear edge of the latter. Diiiiculties have occurred in securing the desired conditions with s'tifl'eners of the type-i1: ques,-

tion hitherto used since, unless the blankjbe given a very thin edge by a very wide scarfV along its rear edge, `the stiffener is'toor rigid at its edge `when it has set in'thefshoe; while, if theyrequisite wide scarf bev given, Y the vextreme 'margin of the lskived fblank fis f' very -weak'and the stiffener is aptr totear at thatplace when being'lasted 'into a shoe. Moreover such stileners, while they -must be firm and rigid, must nevertheless .bev of comparatively,limited thickness and this .is acondition which renders difficultthe production of a wide, small angle scarf.

According to the present inventionthere is provided a thermosplastic stiffenercommore superposedv layers of prising twoj or which A. are chargedv with absorbent fabric thermoplastic substance and are securely d,

united'together to yform a unitary-structure, the stiffener having a relatively thin vand flexible rear edge lby reason of the projection of an unskive'd marginal portion of ang75 outer oneof the layersbeyond the rear mar` 7.

gin of thel adjacent sheet. Y n

The said Outer sheet'will generally be of vsuch nature and thinness as ren-ders itunsuitable for skiving or for more than a very slight'shaving of' 'one of its surfaces;and, j

while in many instances it maybe allowed. to retain its full thickness to thelextreme rear edge of the stifener, snchthinning treatment as it may begiven'will in thev main be brought about by; the applicationr of heat` l and pressure.

Referring .now drawings, j n

Figure 1' is a` sectional: elevation of one formlof in its manufacture;

to the d' accompanying stiffener i, at an intermediate stage Fig. 2 is a. similar view of the same stifi' feiier lata later'stage; n

3 Ais a planof the stiffener 'finished stiften-er; Fig; 431s a planof ya second `torni/ofl Fig( 5 isa sectional elevation of the stifi rfener of Fig. 4 atan intermediate stage in.`

its manufacture; and

Fig. 6 'is a sectional elevation of fener at a later stage. y n n,

lt should here be pointed out that theoutthis sarline ofthe stiffeners shown in Figs, 3 and et is purely byfwa-y of example the outline' will olwiously` be varied according to therespective thicknesses being for example lifteen and thirty thousandths of an inch when measured in the unimpregnated but fiuffedup or. napped condition which will be referred to hereinafter. The thinner of these is, therefore so thin thatit cannot readily he skived when it has been charged with the thermoplastic substance without being torn or shredded.

The thermoplastic stiffening agent with l which both layers are impregnated is conveniently used as the bond between the layers, and the laminated impregnated material is conveniently producedV in sheet form by leading the layers separatelyunder separateY guide rolls into a tank of the molten thermoplastic stiifening agent, the layers being thereafter led under a common guide' roll while still immersed in thev said agent so as to be superposed one upon the other -in the mass of molten material. vThe coinpound sheet, as it leaves the tank, may pass V between rollers which compact the layers together and give the sheet a uniform predetermined thickness before it sets.

After the sheet has cooled and becomes stiff, the stiffener lblanks maybe died out of it by the use of any su'itablemaehine. Instead, however, of proceeding thereupon to skive the rear margin of the whole blank, as has heretofore been the common practice, the rear margin of the layer 3V ct away partly or wholly, as may be desired, so as to leave the then projecting` rear margin of the lower layer uncut, the thin edge of the lower layer then forming all or nearly all of the rear edge of the blank. In the illustrative stiffener the cutting has been so carried outthat the ends 13 of the rear margin of the layer 3 have been left uncut, while the portion intermediate the endsV has been cut away. The purpose of this isto provide. thick, stoutportions atthe locality of the ends 13 so that vat those portions yof the Vstiffener which are to be grasped by the side pincers of the pulling-over machine or to be acted uponby the wipers of the lasting machine when the stiffener is hot and limp, there shall be adequate substance and strength to prevent rupture or undue distorv tion of the stiifener.

y This cutting' operation may conveniently be performed by amachine of the wellknown type which has matrix and presser rollers and fixed knife, the matrix being specially formed with a properly shaped step so as to cause the knife to cut through the layer 3 at a distance (for example one quarter of an inch) fromits rear edge and then to pass betweenthe layersl 3 and 5 from the locality of entry of the knife into the layer 3 to the extreme rear edge of the stiilener,

thereby splitting thelayers apart and removing the severed portion of the layer 3. In producing the stiffener shown in the drawings the step in the' matrix roll was so formed as to cause the knife to leave the end portions 13 of the rear margin of the layer 3 uncut for the purpose described above. And, if desired, the matrix may be so shaped of the layer 5, which has become exposed byv the removal of the rear marginal portion of the layer 3; The purpose of ironing the edge 7 is to thin it somewhat as indicated at 21.` rlhe purpose of ironing the shoulder 11 is first to fuse the layers 3 and 5 together along the line of cut where they may have become slightly parted during the cutting operation, second to increase the extent and change the angle of the bevel 9 until this bevel has the extent and 'inclination indicated at 17 in F ig. 2, and third to cause some of the thermoplastic substance to exude, as indicated at 19, so as to lill up the corner between the shoulder 11 and the face l5. The purpose of ironing the face 15 is to render it smooth and compact since it has usually become somewhat roughened by the passage of the knife over it. As a result there is produced a thin but strong blank which has a wide tapering margin of extreme thinness` and at the same time is of considerable tensile strength when the blank is hot and limp. The finished marginal portion of the layer 5 will usually be of no more than some eight thousandths of an inch in thickness.

To promote adhesion between the layers one face at least of the two contacting vfaces of the fabrics which are to be impregnated is given a nap i. e. is fluifed up. Both these' faces may be so treated so as to augment the absorbent capacity of the material while leaving it readily compressible when saturated and plastic to bring it to a definite gauge and later to obliterate the shoulder 11. The layer 3 may for these purposes have l'one or both of it, feces l'ed but usually l the layer will at most only have its inner y face, if that,^raised, as the desir-e will usually be to keep this layer as thin as possible. l' 1 If desired more than two layers can be used in this way in which case the matrixV will be correspondingly stepped so as in the ycase of three layers (for example) to cause 'the knife to cut througlrone layer, travel some short distance between thatlayer and the middle one to split the layers apart and then plunge lthrough rthe middle layer at some distance from the margin of the blank and finally travel out to the edge lof the blank `between the middle and remaining layer, splitting these apart in so doing.

The blank shown in Figs. l to- 6 is composed of threelayers of the impregnated" fabric superposed .and united after these layers have been cut from an impregnated sheet or sheets. VThe one outer layer is of the full size lof theblank, the otherouter layer 27 is slightly smaller so that the layer i l25 shall project a little beyond it round vsmaller so that not only does the layer 27 project somewhat beyond it round the front and side edges of the blank butj the lrear edge of thelayer 27, where it is cut away at 29, projects rearwardly beyond the rear "edge of the layer 33 by a distance about equal tothe distance by whichthe rear edge of the layer 25 projects rearwardly beyond the rear edge of the layer 27 `at the cut away portionof the latter. The distance between the rear edges of the layer 33 and 25 may equal some half inch or more, while the distance bet-Ween corresponding other marginal portions of these layers may be some quarter of yan inch. All three layers may be of the same character in every way or the intermediate layer may be made from stouter fabric than the others. Conveniently those faces of the unsaturatedv fabric which are to be the inner faces of the outer layers may be fluffed or napped; and, ifv desired for the purpose of increasing the absorbency and compressibility and otherwise modifying the properties of the middle layer as a vehicle for the thermoplastic material, the middle layer may be made from material that has been raised or napped on one or both faces.

The cut layers may be superposed when cold and stiff and then be temporarily secured in relative position by applying a hot tool to the pile of layers at selected spots where, consequently, they fuse together. The layers of the unit thus roughly formed and indicated in Fig. 5 may be finally welded together by heating it until all the layers have softened somewhat and then ironing it so that the layers are welded together,

and "in addition v so that, as previously described,fthe' shoulder formed by the cut away p'frtion29isy obliterated `and the rear edge of .the layer 25,1 where it is exposed be# tween theends 13,fis duly thinned down. This action also Vis used to form in a similar way a bevelled edge round the front and side edoe's of the `'blankV as' indicated at the hazrnid end of Fig. 6.

The intermediate left layery may comprise a fabric `which is thicker or of stiffer material',y

or structures. g. felt, ormay bej charged with' more impregnant, as'desired.- While 1 the impregnant for the outer layers is pref-v erably so chosen as to Give a flexible blank and secure considerabie adhesionbetween the layers, as already` indicated,'and the'imi pregnant of the inner layer may be the same, the fact that the latter layer is encased betweenthe two outer layers, united the one' to the other, admitsof the use of a different impregnant for the inner layer-animpregnant which may be of a less adhesive nature and `stronger and stiffer when cold so'tliat an increased strength is given to the thick portion of the blank without sacrificingy marginal flexibility or introducing any rundue tendency for the layers of the *blank to come apart#l 'A convenient fabric for the layers 5 and 25 and for the layer 27 is a close woven cot ton cloth of plain weave (i. e." with every thread passing over one cross threadand un# derthe next) slightly. fluff'ed or napped .on the face that is to be the inner faceof theA .A con# layer when itis in thestiffenen venient fabric for thelayer 3 or the layer 33 is a cotton cloth the warp of which is of thread of much the same gaugeas that of the cottoncloth just referred to while the weft is of'thread of abouttwice that diameter, and the. weave is such the weft Vpasses over twol acent warp threads, then under the next two warp threads and once more over the next two warp threads giving in efJ fect a plain weave with the wa'rp made up of pairs o-f threads. This fabric may, for the blank shown in Figsfl to 8, bel fluffed or napped on that face of it which will be the inner face in the blank, and for thel blank shown in Figs. 4 to-G may be fluffed or raisedv on one face or both.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is l. A toe stifl'ener for boots and shoes comprising a plurality of superposed layers of absorbent fabric impregnated with a thermoplastic material and securely united together, the middle portion of the upper of the layers being cut away at the rear end of the stiffener to expose an uncut portion of the lower layer whereby the rear margin of the stiff'- ener has comparatively thick end portions and a thinner'intermediate portion.l

.22; Atoe st-ilfenerforrv boots and shoes com-- prising a plurali-ty .of superposedl layers of absorbent fabric impregnatedwith 'a thermoplastic material and securely united together,

*the rear margin of the stiifener having comportion ofvanotherlamina.

LA toe ystiifener foil boots and shoes naving a vplurality of superposed layers of absorbent fabric impregnated with thermoplastic material and securely united together, said layers comprising outer layers of different sizes and an inner layer smaller than either of the outer layers and enclosed between them, said inner layer being charged with more impregnant substance per unit "volume than are the outer layers, the arrangement `being such that from its middle to the rear thereof the thickness of the stiffener is made up first of vthe thickness of all the layers, then of that of the outer layers, vandrthen of that of one only of the outer layers.

5. The method of manufacturing a stiffener which comprises cutting from a piece of laminated sheet material impregnated with a thermoplastic substance a blank of thedesiredoutline and thinning one margin of the blank by cutting awayl the margin of one of the laminae leaving uncut that of another.

6. The method of manufacturing a stiffener which comprises cutting from a piece of laminated sheet material impregnated 7. The method of manufacturing a stiff-1 ener which comprises cutting from a piece v oflaminated sheet material impregnated with a thermoplastic substance a blank of the desired outline, thinning one margin of the blank by cutting away the margin of one of the laminae and leaving uncut that of another, and obliterating the shoulder which results from the cut by application of heat and pressure.'

8. The method of manufacturing a stiffener which comprises cutting from apiece of laminated sheet material :impregnated with a. thermoplastic substance a blank of the desired outline, thinning one margin ofv the blank by cutting 4away the margin of one of' the laminas and leaving uncut that of another, and thinning the extreme margin of uncut lamina by application of heat and pressure. s v

y 9. A toe stilfener for boots and shoes comprising a plurality-of superposed layers of absorbent fabric impregnated-with a thermoplastic material and secu-rely united tos gether, a part of one ofthe outer layers projecting beyond the edge of an adjacent shorter layer to for-ni a thin flexible rearmargin of the stiffener, the rear edge of said shorter layer being compacted and beveled. In testimony whereof I have signed my name to this specification.

FRED Ricks. 

